what matters for an engine to work with TBI. is it only the cam? what are the specs for cams that will work with the TBI.

 

i believe almost any cam will work with a TBI if the computer chip is properly tuned, usually when people say it will be "TBI friendly", they are stating that it will still work well with the stock chip.

 

I think "TBI friendly" was well defined above. To be "TBI friendly" you have to pay paticular attention to the cam's LSA. The more duration the cam has, the more LSA that's needed to smooth out the idle so the ECM stays happy.

 

can u givbe me examples of the duration to LSA that works. i would be using the stock chip. i have the burning stuff but haven't started using it yet.

 

Here's some rough estimates:

180-190* duration (@ .050") 109 LSA
191-201* duration (@ .050") 110 LSA
202-212* duration (@ .050") 111 LSA

etc, etc...

Remember these are all estimates though and each engine has the potential to react differently. Also playing with fuel pressure and timing can affect the cam's ability to work with the ECM.

 

witht eh speed density system, the tbi needs good vacuum. Low erratic vacuum will not make the ecm happy, even with tuning. Remember, the ecm uses vacuum, not mass flow rate of air as one of its perameters to determine how much fuel is needed.

 

Iroc22 response with these
191-201* duration (@ .050") 110 LSA
202-212* duration (@ .050") 111 LSA

Is correct but I usually recommend a lobe separation of 112+ for TBI engines. That is why the LT1 cam runs so well in the TBI cars with it's 115 LSA.

 

I'm using the Crane Compucam 2030 Hydraulic Roller in my 350 TBI (with custom chip)
Like said above, good vacuum signal is recommended.
I'm getting 317 HP and over 380 ft/lbs (flywheel)
Cam Specs:
Duration @ .050":I=204,E=214
116 degree Lobe Separation
Lift: I=.429", E=.452"
-Rich-

 

I will be running the ZZ4 cam (208/221 duration .474/.510 max lift 112* LSA) when I swap out the 305 TBI for a 350 TBI.

 

It's proportional to the duration. The stock L03 cam only has a LSA of 109*. The more duration, the more LSA that is needed to generate vaccum so the ECM stays happy.

 

Correct. I should have put that in there but I doubt that anyone is going to run a cam with less than 200 duration and most aftermarket cams don't have any more than 114 degrees of lobe separation. The ZZ4 cam really pushes the duration to lobe separation ratio.

I just don't want to see someone buy a 230 degree duration cam with 110 degrees of lobe separation and then wondering why it runs like crap in a TBI engine without a LOT of chip work.

 

Hmmm....
I wouldn't say mine runs like crap at all!
But then again I don't have an L03 and am running the Crane 2030 FT with 110 LSA....

 

what all do you have done to your 350